In charged-particle beam devices, the representative of which is a scanning electron microscope (: SEM), it is necessary for their high-resolution implementation to irradiate the surface of a sample with a stable electron beam. For example, in a semiconductor critical-dimension measurement device where the SEM is utilized, there has been a significant request for even more stable irradiation with the electron beam. Here, this request has been made in accompaniment with the microminiaturization in the dimension of a measurement pattern in recent years.
In the semiconductor critical-dimension measurement device, the dimension of a measurement pattern is measured as follows: Namely, the measurement pattern is scanned with an electron beam. Moreover, a signal of secondary electrons generated from the sample is detected, then being formed into a SEM image. Finally, the above-described dimension is measured based on this SEM image. If, however, the measurement device is set up at a location whose external environment is undesirable, there exists the following possibility: Namely, an influence exerted by an external disturbance (such as magnetic field or vibration) will disturb a relative deflection of the electron beam with respect to the sample, thereby giving rise to the occurrence of an image failure. Also, if the set-up condition is undesirable, there also exists the following possibility: Namely, a magnetic field or vibration, which is generated by the measurement device' main body itself, will also exerts an influence onto the image formation or measurement. Then, the occurrence of the image failure results in the occurrence of a lowering in sharpness of the SEM image, or the occurrence of a distortion of the SEM image. As a result, it becomes difficult to make the stable measurement on the dimension.
In PATENT LITERATURE 1, the disclosure has been made concerning a technique for correcting a shift of the electron beam's irradiation position. Here, this position-shift correction is made by setting up, outside the electron-beam irradiation device, a magnetic-field detector for measuring an external magnetic field as described above. Also, in PATENT LITERATURE 2, the explanation has been given regarding a technique for correcting a deflection signal. Here, this deflection-signal correction is made as follows: Namely, a vibration gauge for detecting the vibration is set up outside the charged-particle beam device. Moreover, the measurement on the vibration is made, then correcting the deflection signal on the basis of vibration information acquired by this measurement. Furthermore, in PATENT LITERATURE 3, the explanation has been given concerning a technique for making the analysis of the external disturbance or the like by making the fast-Fourier-transform (: FFT) analysis of the SEM image.